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Energy saving soft starter for 3-ph. SQ Induction motor


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I am a final year engineering student of electrical engineering(based in India).As per our university curriculum i am carrying out a project titled 'energy saving soft starter for 3 phase induction motor'.We are already through with the soft starter part,but are unable to carry out the energy saving part.Basically we are stuck with the hardware part required for energy saving(being electrical engineers, we do not have much knowledge of electronic hardware).

The componenets which we have used for the soft starter part are as follows(this can give you a rough idea of the scheme which we have followed):



1)For 1 H.P. to 5 H.P. motors

2)Microcontroller used - AT89c51 (Atmel)

3)Soft start with time starting (0.5 to 120 sec.)

4)Optimize ON/OFF.

5)Current limit ? enable / disable.

6)Pedestal voltage (30% to 70%)

7)Power factor detection (auto / default)

8)Protection - Phase failure

Phase reversal

Over voltage



9)User interface 4- key keypad

16 X 2 alphanumeric LCD Display

The thyristors used are Triacs(BTA41)...3 nos.(1per phase).

So if anyone can help, please e-mail me at this id.

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Hello guptealok


Welcome to the forum.


The energy saving algorithms are based on work done by Frank Nola of NASA back in the late 70s.

Do you have a good understanding of the NASA algorithm?


Once you understand the algorithm, there should not be too much difficulty in making the hardware.


I would suggest that you do a patent search for Nola and Nasa and that will bring up some of the original publications.


If you need further information, I can give you a description.


You may also find looking at my paper at http://www.LMPhotonics.com/energy.htm is beneficial.


Best regards,

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